1. Technical Field
The invention relates to systems having hot-pluggable power consumption devices, hot-pluggable power supplies including a non-volatile memory storing their own characteristics and a power management unit providing the optimal power distribution to the power consumption devices as a function of the present power supplies. More particularly, the present invention relates to a method of managing the power supplies in a power consuming system.
2. Background
The system involved in the invention can be either a device used in telecommunication networks, such as a router or switching device, or a data processing device that includes a plurality of processors wherein one of the processors acts as a control processor managing the power consumption of the other processors.
Such a system as illustrated in FIG. 1 includes the following components.
(i) a set of power supplies 10, 12, 14 that may be of different types, supplying some or all of the various voltages required by the system (e.g. +3.3V, +5V, xe2x88x9248V, and +12V from 220V AC), and that can be inserted in or removed from the system at any time,
(ii) slots that can receive power consumption devices 16, 18, 20 which can be added or removed at any time,
(iii) a Control Point 22, provided with a CPU and some memory, capable of reading information that comes from serial EEPROMs over an I2C serial bus 24 connecting the power supplies and the power consumption devices to the Control Point, and controlling the supply of power to the slots, and thus to the devices they contain, the Control Point being permanently powered, and
(iv) a power supply distribution network of the various voltages to the Control Point and to the slots, including the capability for the Control Point to control slot powering.
Additionally, the Control Point can access the required power information for any device and any voltage, either through an EEPROM located in the consumption device that contains this information, or through software tables that give this information based on the identification of the inserted device. The Control Point further has an operator interface means such as a console 26.
The design and manufacturing cost of power supplies in the system is an important factor, because savings can be accomplished there. This is why a power supply is not designed straight away to withstand the maximum theoretical load of a system filled with the power consumption devices that have the highest power requirements, but rather to provide the ability to increase the system capability as its power requirements get higher. This way, the cost of small configurations remains competitive compared with their competitors.
The Control Point must, among other things, manage the feeding of slots and devices inserted into them based on the following parameters:
(a) consumption characteristics of power consumption devices,
(b) power priority assigned to the power consumption devices in case of a conflict,
(c) capability of power supplies to withstand the load required by the Control Point and by the power consumption devices inserted into the slots, and
(d) power redundancy if this one is desired for power supplies (i.e. should any of the power supplies fail, remaining power supplies will still withstand the load)
A conflict occurs when the system power supplies cannot withstand the overall load of the devices, because either there are too many devices compared with power supplies capability, or because one or several power supplies failed or were removed. In such a case, the Control Point switches off the devices having the lowest power priority, in order to meet each power supply capability and operating range.
The Control Point can use the console for showing devices not powered in case of a conflict, and requesting that an operator should either add one or more power supplies or remove these devices. The Control Point may also utilize the console for displaying the current redundancy status (i.e. whether redundancy still exists, further to a power supply failure or removal) and for displaying the remaining margin for feeding additional devices when there is no conflicts, so that the operator can decide whether he must plan the addition of one or several power supplies when he wants to add other devices.
Prior art solutions for performing the above tasks are based on:
1. either accessing a description of power maximum capability characteristics for any voltage powered by a power supply, or
2. a feedback mechanism from any power supply to the Control Point, enabling to determine the limit and the remaining margin (see, e.g., PCT application WO 96/19764).
Type 1 solutions have the following disadvantages:
(a) They impose constraints on power supplies design and manufacturing, requiring that the supplied voltages be independent. That is, the power used from a voltage does not affect the amount of power that remains available to another voltage. This kind of constraints substantially increases power supplies design and manufacturing costs, or
(b) they do not require any independence among voltages. However, in such a case, either the Control Point software features remain basic and do not get the most of the power supplies. For example, as it requires more power supplies than needed, the control point software cannot accurately estimate the remaining capability. Thus, it cannot enable an optimum redundancy operation within a system provided with different types of power supplies. This increases the overall cost of the system as the latter requires more power supplies than needed, or
(c) the Control Point software can manage optimally the different types of power supplies, but need to know each type. This results in a complexity that increases with the number of types to be managed. This, in turn, increases the testing costs of the system, along with maintenance costs if bugs occur that, in turn, increases directly or indirectly the system overall cost.
Additionally, when creating a new type of power supply (further to a technology improvement, a cost reduction action, or a system evolution), the Control Point software must be updated and the new release must be dispatched that, in turn, also involves additional costs.
Type 2 solutions are not satisfactory either, as they require some intelligence either in the power supplies or around them in the system, that generates a cost equal to or greater than the cost of type 1 solutions.
It is therefore an object of the present invention to provide an improved power managing system.
It is another object of the present invention to provide a method for managing power supplies in a power consumption system.
To achieve the foregoing objects, and in accordance with the invention as embodied and broadly described herein, a method for managing power supplies in a power consuming system having multiple power consumption devices to be powered up by one or several voltages among a set of voltages V1, V2 . . . Vm is disclosed. The set of voltages are provided by multiple power supplies, wherein each power supply provides at least one voltage. The power consuming system also includes a control point for controlling the power supplied to the power consumption devices. The method includes determining a set of linear inequations linking each variable PV1, PV2 . . . PVm, representing the power being consumed for each voltage, or combinations of several variables, to predetermined power limits PVC. Next, the real power value (P) requested for each voltage in order to power up each one of the first plurality of power consumption devices is determined. Subsequently, each real power value is divided by the number of power supplies (p) providing power for the associated voltage in order to determine the components of a power consumption vector (PC) for each power supply. Next, the variables PV1, PV2 . . . PVm are replaced in the inequations by the corresponding components of the power consumption vector for each power supply (PC) in order to obtain a requested power value for each inequation. The requested power value is then compared to the predetermined power limits (PVC) and the control point determines that a new power supply is requested if at least one of the requested power values is greater than the predetermined power limits.